My heart also goes out to you for the loss of the love of your life. My fiancé passed in a plane crash when I was 24 and he was 26. I know it is not the same but just wanted to share that with you so you know that my heart does feel with you at the depth of your loss. They say time heals all wounds, but that is a lie. We don't ever stop loving the man we lost before his time.

Because of your past loss, I would highly encourage you to talk about the changes with your T from the point of how they impact you and your sessions.

You said your husband first had a stroke. That was sudden change. It was drastic.
Your T having a child and transforming from a young adult into a mother is also a drastic change.

In your past, you saw that a drastic change can lead to someone you love dearly being removed from your life. Drastic change = HUGE loss / BIG pain / emotional trauma .

It will be very natural for you to emotionally "panic" at a big change in the next person closest to you. In this case it is T.

You know you don't want T to change and you know you logically can accept T making changes. But the emotional uncertainty is what you need to addess. So keep the focus on you and maybe say something like "I need to go over a few things with you. These are changes I see in you. This is how those changes make me feel."